Hang ten is the name of a surfing maneuver in which the surfer rides with all 10 toes draped over the front edge of the surfboard. For this to be accomplished, it is necessary for the back end of the board to be in the wave so that the water will hold it down. Before hanging ten, you might want to try hanging five:
The hang five is easier, they say. It is half the hang ten. Instead of both feet, you stand with one foot back…. For many, just riding the wave is enough.
— The Cape Argus (South Africa), 18 May 2008
Hang ten dates to the 1960s, the same decade Annette Funicello began starring in a number of "Beach Party" movies.
The expression "I wouldn't touch it (or 'him' or 'her') with a ten-foot pole" conveys contempt or extreme dislike. Originally, a ten-foot pole was simply a measure of distance. Famed 19th-century songwriter Stephen Foster used it to describe the depth of a mud hole in his popular song "Camptown Races," which contains the lyrics, "De blind hoss stick'n in a big mud hole … Can't touch de bottom wid a ten foot pole. Oh! doodah day!" In 1884, American author William Dean Howells used the phrase metaphorically (in his novel The Rise of Silas Lapham) to characterize a person in the declaration, "Do you suppose a fellow like young Corey, brought up the way he's been, would touch mineral paint with a ten-inch pole?" It was also in the late 19th century that the slangy phrase "wouldn't touch it with a ten-foot pole" emerged with its sense of unwillingness to involve oneself with a person or thing.
Ten-gallon hat has been used to refer to a cowboy hat since the early 1900s. The likeliest and most obvious explanation for gallon being used in this way is that the hat, like the gallon measurement, was extremely large, perhaps the largest hat in the West. Just as the word pint is often used to describe what is smaller than average (as in pint-size and half-pint), gallon came to signify what is larger than average, even enormous. Large cowboy hats thus became known as ten-gallon hats.
Another explanation is that the wide-brimmed hats worn by cowboys and ranchers were originally decorated with braids at the base of the crown. A Spanish word for braid is galón. And so, it is said, derived the expression ten-gallon hat, but evidence covering this etymology has yet to be substantiated.